HIV Dual Therapy Matches Standard Triple Cocktail

A two-drug regimen for HIV did as well in controlling the virus as a standard triple-drug cocktail, researchers found.

Action Points

A two-drug regimen [ritonavir-boosted lopinavir (Kaletra) plus lamivudine] for HIV did as well in controlling the virus as a standard triple-drug cocktail.

Note that patients getting two drugs reported significantly fewer grades 2 and 3 clinical adverse events compared with those in the triple-drug arm.

A two-drug regimen (lopinavir/ritonavir plus lamivudine) for HIV did as well in controlling the virus as a standard triple-drug cocktail, researchers found.

After 48 weeks of therapy with the dual-drug regimen, 88.3% of patients had undetectable virus by standard tests, according to Pedro Cahn, MD, PhD, of Fundación Huesped in Buenos Aires.

The three-drug regimen led to viral control in 83.7% of patients, which was non-inferior to the dual regimen, Cahn reported at the 2013 European AIDS Conference in Brussels.

Importantly, among those getting three drugs, there was a greater number of grades 2 and 3 adverse events and more patients stopped therapy for reasons of toxicity and tolerability, Cahn reported.

Most HIV regimens include drugs from two or more classes, since early mono- and dual-therapy regimens led quickly to treatment failure.

An expert review last year, however, suggested that the issue remains open, especially since some newer drugs have a high barrier to the development of genetic resistance.

It is currently not difficult, Cahn noted, to get viral loads below the level of detection -- defined as a plasma viral load of fewer than 50 copies of HIV RNA.

The challenges, he said, include such things as tolerability, toxicity, and simplicity of drug therapy. In principle, a two-drug regimen could be easier to take for many people, as long as it didn't compromise antiviral activity.

To test the idea, he and his colleagues randomly assigned 426 treatment-naïve people to get either ritonavir-boosted lopinavir (Kaletra) plus lamivudine or lopinavir/ritonavir plus either lamivudine or emtricitabine (Emtriva) in combination with another nucleoside reverse transcriptase inhibitor selected by the investigator.

The primary endpoint was the proportion of patients in each arm with undetectable viral load at 48 weeks, but the researchers also investigated safety, tolerability, resistance, and immunological responses.

The difference between the arms at the end of 48 weeks was 4.6 percentage points in favor of the two-drug regimen, Cahn said, but the 95% confidence interval ranged from minus 2.2 to 11.6, so the difference was not significant.

There was also no significant difference when the analysis was restricted to those whose baseline HIV RNA was greater than 100,000 copies.

Cahn also reported:

There were 22 cases of virological failure, 10 in the dual-drug arm and 12 in the triple-drug arm.

On average, increases in CD4-positive T cells were similar -- 227 and 217 cells per cubic millimeter of blood for dual- and triple-drug therapy respectively.

Patients getting two drugs reported 65 grades 2 and 3 clinical adverse events, compared with 88 for those in the triple-drug arm, a difference that was significant at P=0.007.

One serious adverse event, a case of gastritis in the dual-therapy arm, was thought to be related to study drugs.

One patient in the dual-therapy arm stopped for reasons of toxicity or tolerability, compared with 10 triple-drug patients, a difference that was significant at P=0.01.

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